Recently, machine translation software is widely utilized in order for a user to read Web page on the Internet. For example, in case of reading a Web page of on line-news reporting a trend of foreign countries in real time, the machine translation software is utilized. In general, the Web page of on line-news includes a headline and an article body. The headline represents a summary of the article body. The Web page is described in a first language (For example, English) and the machine translation software automatically translates the Web page into second language (For example, Japanese). The user whose native tongue is the second language reads the Web page after the machine translation. In this case, before the user reads translated sentences of the article body, he often reads a translated headline in order to decide whether to read the article body or not. Accordingly, translation of the headline is more important than translation of the article body.
However, in this news article (For example, English article), new proper nouns not registered in a translation dictionary are often used and a style of the English article is unique. Accordingly, machine translation is difficult. Especially, the headline (a title of the article) is fragmentally described on the assumption of background knowledge of an English-speaking people. Accordingly, machine translation of the headline is extremely difficult.
As mentioned-above, the style of news article headline is unique and its machine translation is quite difficult.